A novel Si/SiGe heterostructure for quantum dot spin qubits

ORAL

Abstract

Motivated by a desire to increase the energy splitting between the two low-lying valley states in a silicon quantum well, a Si/SiGe heterostructure is grown via UHV-CVD with a ~1 nm layer of SiGe buried ~2 nm beneath the upper interface of a silicon quantum well. High resolution STEM measurements confirm that this thin epitaxial layer is abrupt on the side facing the substrate and gradual on the side facing the surface. We report Shubnikov-de Haas and quantum Hall measurements, finding a transport mobility in excess of 100,000 cm2/(V s) at 6 x 1011 cm-2 carrier density and a series of stable oscillations in measurements of the longitudinal voltage as a function of magnetic field and carrier density (a fan diagram). We report both activation energy measurements in the quantum Hall regime and measurements of the excited state spectrum in gate-defined quantum dots fabricated in this material.

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Presenters

  • Thomas McJunkin

    Department of Physics, University of Wisconsin-Madison, University of Wisconsin - Madison

Authors

  • Thomas McJunkin

    Department of Physics, University of Wisconsin-Madison, University of Wisconsin - Madison

  • Evan R MacQuarrie

    Department of Physics, University of Wisconsin-Madison, University of Wisconsin - Madison

  • Samuel Neyens

    Department of Physics, University of Wisconsin-Madison, University of Wisconsin - Madison

  • Brandur Thorgrimsson

    Department of Physics, University of Wisconsin-Madison, University of Wisconsin - Madison

  • Joelle Corrigan

    Department of Physics, University of Wisconsin-Madison

  • John Dodson

    Department of Physics, University of Wisconsin-Madison, University of Wisconsin - Madison

  • Donald E Savage

    University of Wisconsin-Madison, Department of Materials Science and Engineering, University of Wisconsin-Madison

  • Max G Lagally

    University of Wisconsin-Madison, University of Wisconsin, Department of Materials Science and Engineering, University of Wisconsin-Madison

  • Mark G Friesen

    Department of Physics, University of Wisconsin-Madison, University of Wisconsin-Madison, University of Wisconsin - Madison

  • Susan Coppersmith

    Department of Physics, University of Wisconsin-Madison, University of Wisconsin-Madison, University of Wisconsin - Madison

  • Mark Alan Eriksson

    Department of Physics, University of Wisconsin-Madison, University of Wisconsin-Madison, University of Wisconsin - Madison